Update Httparty to ~> 0.13.0 to avoid CVE-2013-1802

Also updates gems
Adds set `:protection, :except => :path_traversal` to app.rb

This prevents eating/omission of %2F%2F when called from spec/requests/magickly_app_spec.rb:114

More information: https://github.com/sinatra/sinatra/issues/808